Inverse clevis safety belt buckle

ABSTRACT

A safety belt buckle wherein a conventional latch for engaging an apertured tongue of a conventional connector is pivotally seated within the base loop of an inverse clevis having an opening for insertion of the tongue and a solid transverse interior surface confining the engaged end of the latch against pivotal displacement incident to latch angularity under ultimate tensile belt loads sufficient to deflect the channel sides of conventional stamped frames characteristic of prior art seat belt buckles.

BACKGROUND OF THE INVENTION

Known prior art safety belt buckle constructions which typicallyincludes a stamped open frame with channel sides limiting pivotal latchdeflection under load include the following U.S. Pat. Nos. 3,131,451;3,237,256; 3,242,546; 3,274,655; 3,277,548; 3,449,800; 3,465,393;3,483,599; 3,588,969; 3,623,191; 3,639,951; 3,686,720; 3,716,895;4,015,094; 4,052,775; 4,060,879; 4,064,603.

Under heavy test loading it has been found that the channels of suchtypical safety belt buckle frames formed as sheet metal stampingsprovide limited resistance for retaining the latched tongue againstdeflection incident to the angularity between the latch pivotalengagement with the reaction surface of the frame and the latchengagement with the apertured tongue of the connector. Another criticalarea of limited strength in the prior art stamped frames is the reactionsurface for the latch normally formed with a right angle bend at the endof the frame which is engaged by the base of the latch. In each caseheavy loading on the belt subjects the stamped channels and reactionbase of the frame to critical bending loads inherently incident to theunsupported extremities of the stamping channel and angle edges.

SUMMARY OF THE PRESENT INVENTION

In order to provide an inherently stronger substitute for theconventional stamped open frame with channel sides, and inverted clevisconstruction has been employed in the buckle disclosed herein which isformed as a sheet metal stamping doubled over to provide a loopcentrally slotted for insertion of the connector tongue with sides ofthe loop as well as an angle seat adjacent the tongue slot forming apivotal base for a latch which in its engaged position with theconnector tongue registers against a solid portion of one side of theclevis unyieldingly resisting any deflection load imposed on the latchthrough belt tension under the most severe test loading.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of clevis and connector components of a preferredembodiment with plastic cover shown in phantom;

FIG. 2 is a side elevation with latch and release lever added;

FIG. 3 is a bottom view of the clevis, latch and lever components;

FIG. 4 is a central sectional side elevation of the clevis and latchshown in FIG. 2;

FIG. 5 is a plan view of the clevis stamped blank before forming;

FIG. 6 is a plan view of the clevis per se;

FIGS. 7, 8 and 9 are respective plan, side and end views of the latchper se;

FIGS. 10, 11 and 12 are respective plan, side and end views of thespring per se illustrated in FIGS. 2A, 3A;

FIG. 13 is a plan view of the stamped blank for the spring illustratedin FIGS. 10, 11 and 12 before forming;

FIGS. 14, 15 and 16 are respective plan, side and bottom views of theswitch housing per se illustrated in FIGS. 4A and 5A.

With reference to FIGS. 1, 2 and 3 the main elements of the preferredembodiment include inverse clevis 20, latch 21, connector 22, andrelease lever 23 having projections 24 engaging latch extensions 25.Slotted opening 26 in the loop end of clevis 20 admits insertion ofconnector tongue 27 having latch engaging aperture 28 with an arcuatesurface 29 adapted to engage arcuate end 30 of latch 21.

Plastic cover 31 shown hatched in FIGS. 1 and 2 includes guide opening32 for connector tongue 27 and is riveted at 33 through apertures 34 inthe ends of clevis 20 with plastic inserts 35 and 36 adapting the endsof clevis 20 for connection to a belt end (not shown). The plastic end32 of cover 31 also provides an anchor point for release lever pivot 37accommodating movement of latch extensions 25 to dotted line position25a, against a latch spring hereinafter described, moving latch end 30to a position for releasing tongue 27.

With the latch engaged as illustrated in FIGS. 2 and 4 the entirearcuate end 38 of latch 21 engages loop end 39 of clevis 20 belowslotted opening 26 thus providing reaction support not only at theextremities of clevis 20 on either side of slotted opening 26 but alsoin the intermediate space below the slotted opening. It will also beseen that the entire solid upper surface 40 of clevis 20 serves toprevent any deflection of latch end 30 above the latching levelillustrated in FIGS. 2 and 4 incident to the angularity of the latchtongue under high tensile loading of the belts (not shown) on the buckleelements. Thus, the superior strength of the inverse clevis, whichsubstantially limits critical stresses to predominantly tensile andcompressive loads and avoids the bending stresses imparted tounsupported channel edges and angle bends of prior art buckle frames,provides an inherently stronger buckle within the parameters of equalsize and material thicknesses.

With reference to FIGS. 7 and 8 angularity in the order of 15° betweenthe upper latch surface 41 and horizontal latch surface 42 together withlatch end surface 30 normal to surface 41 results in an arcuate contactline 43 with arcuate connector tongue edge 29 of aperture 28, alsoformed with all sides normal to the surface plane of connector 22,inclined at approximately 5° relative to the pivotal axis of latch end38 thereby providing a release component incident to belt tension on thebuckle which is less than the angle of friction of the steel materialsemployed so that no extreme belt load can ever produce disengagingpivotal movement of the latch, although some assist in minimizing manualrelease forces required on the release lever under belt tension testloads is accomplished. Latch and connector contact surfaces 30 and 29are preferably formed with a matching radius and with a latch harnesssubstantially exceeding the connector so that any "brinelling" incidentto high belt loads will take place on the connector increasing theinitial line contact to a perfectly matching area contact withoutexceeding the ultimate strength of either element and without the needfor special fitting of the contact surfaces other than provision of thesame initial radius on surfaces normal to the face plane of eachelement.

The buckle has been described above with reference to FIG. 1illustrating the relationship of connector and clevis with coverindicated in hatching; FIG. 2 adding the latch and release leverelements; FIG. 3 showing a bottom view of the clevis with opening forlatch extensions engaged by release lever projections; FIG. 4 indicatingthe engaged relationship of latch and clevis per se; FIG. 5 illustratingthe initial blanked configuration of the clevis stamping; and FIGS. 7, 8and 9 showing the detailed construction of the latch per se.

In FIGS. 2A and 3A an additional return spring 44 required for biasingthe latch to engaging position which will resiliently yield to insertionof the connector tongue is illustrated superimposed on the similar FIGS.2 and 3. Such return spring is illustrated per se in FIGS. 10, 11 and 12and in initial blank form in FIG. 13. Spring 44 is anchored toprojections 45 and 45' extending within opening 46 for latch extensions25 and switch assembly 47, illustrated in detail in FIGS. 4A and 5A.With reference to FIGS. 11 and 13 notches 48 formed in the base ofspring 44 engage the clevis stamping on each side of projection 45' andnotches 49 formed in the ends of spring arms 50 engage projection 45 toprovide an upward spring bias through spring arms 51, having a freeposition 52, against the underside of latch extensions 25. FIG. 13illustrates initial blank form of spring 44 before being folded intooperative configuration shown in FIGS. 10, 11 and 12, the latter figureomitting spring arms 50 to illustrate more clearly the spring arms 51per se.

With reference to FIGS. 4a, 5a, 14, 15 and 16, switch assembly 47includes a switch housing 53 illustrated per se in FIGS. 14, 15 and 16in which an electrical switch for opening a normally closed circuitbetween two electrical lead wires 54 is produced by engagement of theleading edge of connector tongue 27 with projection 55 of a rotatablepin 56 having a coiled spring 57 wound on one side with each end thereofnormally contacting lead extensions 58 associated with lead wires 54,rotation of projection 55 upon engagement of connector tongue 27 servingto rotate one end of coil spring 57 out of electrical contact breakingthe circuit. Plastic switch housing 53 includes a pair of lead wirepassages 59, a pair of holes 60 for spring pivot 56, notched projection61 for engaging clevis projection 45, and recess 62 for accommodatinglead wire connections.

Assembly of the buckle is accomplished by the steps of sliding the latchlaterally into position within the clevis; inserting the switch housing;placing the spring over the switch housing; deflecting the ends ofspring arms 50 to engage notches 49 with clevis projection 45; snappingcover frontal end 63 having retention tangs 64 into engagement with loopextremities 39 of clevis 20, thereby positioning preassembled releaselever 23 with its projections 24 into operative engagement with latchextensions 25; inserting plastic end spacer 35 between clevis ends;insertion of plastic sleeve 36 in clevis opening 67, applying mainplastic cover body 65 over the clevis assembly and application of rivet33 to complete assembly of the buckle.

I claim:
 1. A safety belt buckle characterized by a sheet metal loopformed clevis having apertured ends for attachment to a first belt end,a fully surrounded slot in the clevis loop end extremity, a connectorhaving an apertured end for attachment to a second belt end and a tongueinsertable through said slot into close proximately with one side ofsaid clevis, said tongue having an apertured end adapted for latchengagement, a latch having a reaction end extending beyond bothextremities of said slot pivotally seated against slotted and unslottedportions of said loop end extremity within said clevis adjacent saidslot having a latch projection engageable with said tongue apertured endand said one side of said clevis, resilient means biasing said latchtoward said engaging position deflectable in response to manualinsertion of said tongue, and manually operable means to deflect saidlatch and resilient means to a tongue releasing position.
 2. A buckle asset forth in claim 1 including an access aperture in said one side foraccommodating said manually operable means.
 3. A buckle as set forth inclaim 2 wherein said manually operable means comprises an exposedpivotally mounted release lever having side extensions through saidaperture.
 4. A buckle as set forth in claim 3 including latch sideextensions engaged by said lever side extensions.
 5. A buckle as setforth in claim 4 wherein said resilient means comprises a spring mountedon the other side of said clevis.
 6. A buckle as set forth in claim 4wherein said resilient means comprises a spring mounted on the otherside of said clevis said spring including side extensions engaging saidlatch side and extensions.
 7. A buckle as set forth in claim 6 includingan electrical switch located between said spring side extensions.
 8. Abuckle as set forth in claim 6 including an electrical switch locatedbetween said spring side extensions said switch having a pivoted elementengaged by said connector tongue in its latched position.
 9. A buckle asset forth in claim 8 wherein said pivoted element has a coiled springmounted thereon adapted to open an electrical circuit in response totongue actuation of said pivoted element.
 10. A buckle as set forth inclaim 1 including a plastic housing frontal loop end piece having aslotted opening with guide surfaces for leading said connector tonguethrough said clevis slot to facilitate buckle engagement.
 11. A buckleas set forth in claim 3 including a plastic housing main body having anaccess aperture for said release lever and a pair of end extensionscovering said clevis aperturned ends.
 12. A buckle as set forth in claim11 wherein said housing includes a clevis end spacer insert recessed fora pair of switch lead wires.
 13. A buckle as set forth in claim 12wherein said housing includes a sleeve insert extending through alignedapertures in said clevis providing a shield for said lead wires andpassage for said first belt end.
 14. A buckle as set forth in claim 13wherein said plastic cover main body is retained in assembled relationwith said clevis by fastening means passing through aligned holes insaid cover and clevis ends.